How to create a typing text-object animation ?
You can use the Blender Typewriter Addon:

http://urchn.org/post/typewriter-blender-addon

copy and paste the code into the Text Editor, then press alt + p to run the script.

Select your text object and you'll find a new panel into the Font Propery Panel:


Type the text in "source_text" field (NELLY).

Go to frame 0 and insert a keyframe for the character_count = 0 (mouse over the field and press i)

Go to frame 75, change character_count to 5 (text length) and press i

EDIT: Animation Nodes Addon

If you need more control (such as animating letters size, rotation...), you could use the Animation Nodes Addon.

Here you can find a video showing an advanced text manipulation:
https://www.youtube.com/watch?v=li7R01PyXuI&amp;index=26&amp;list=PLFSQhJg6cGLKq8WbouMNBOHbMd7xUhuom